In recent years, efforts have increasingly been made to produce industrially complex carbohydrates, such as secreted oligosaccharides. This has been due to the roles of such compounds in numerous biological processes in living organisms. Secreted oligosaccharides, such as human milk oligosaccharides (“HMOs”), have become particularly important commercial targets for nutrition and therapeutic applications. However, the synthesis and purification of these oligosaccharides have remained a challenging task. One of the simplest important human milk oligosaccharides is 3-O-fucosyllactose β-D-galactopyranosyl-(1→4)-(α-L-fucopyranosyl-(1→3))-D-glucose (“3-FL”):

Several biological activities of 3-FL have been reported including its prebiotic, antibacterial, antiviral, immune system-enhancing and brain development-enhancing activities. These activities of 3-FL have made it a potentially attractive additive for nutritional and therapeutic products. However, it has been difficult to obtain 3-FL in pure form except at very high cost.
3-FL has been isolated from human milk by very costly and complicated chromatographic procedures. 3-FL synthesized by enzymatic, biotechnological and chemical processes (Dumon et al. Biotechnol. Prog. 20, 412 [2004], Fernandez-Mayoralas et al. Carbohydrate Res. 154, 93 [1986], and Pereira et al. Heterocycles 84, 637 [2012]) has been isolated as an amorphous material and thus it has been very costly to purify. This has made previous methods of making 3-FL too costly for commercialization.
Crystallization or recrystallization is one of the simplest and cheapest methods to separate a chemical product from contaminants and obtain it in pure form. In addition, crystalline modifications (polymorphs) of a solid compound is an important factor in its product development, because different crystalline forms affect the compound's properties—for example its thermodynamic stability, solubility, density, hygroscopicity, electrical properties (such as dielectric constant, conductivity), mechanical properties (such as friability, hardness, breaking strength, elasticity), optical properties (such as colour, transparency, refraction), etc.—diversely.
For this reason, ways have been sought for obtaining crystalline 3-FL.